[PATCHv3 0/2] blk-mq: force completion

[PATCHv3 0/2] blk-mq: force completion

[Keith Busch]

I've renamed the newly exported function from
__blk_mq_complete_request() to blk_mq_force_complete_rq() and added
kerneldoc for its intended usage.

Reviews and Acks from previous versions are not included for PATCH 1/2
since the name changed.

Keith Busch (2):
  blk-mq: export blk_mq_force_complete_rq
  nvme: force complete cancelled requests

 block/blk-mq.c           | 15 +++++++++++++--
 drivers/nvme/host/core.c |  2 +-
 include/linux/blk-mq.h   |  1 +
 3 files changed, 15 insertions(+), 3 deletions(-)

-- 
2.24.1


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[PATCHv3 1/2] blk-mq: export blk_mq_force_complete_rq

[Keith Busch]

For when drivers have a need to bypass error injection.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 block/blk-mq.c         | 15 +++++++++++++--
 include/linux/blk-mq.h |  1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index cac11945f602..560a114a82f8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -556,7 +556,17 @@ static void __blk_mq_complete_request_remote(void *data)
 	q->mq_ops->complete(rq);
 }
 
-static void __blk_mq_complete_request(struct request *rq)
+/**
+ * blk_mq_force_complete_rq() - Force complete the request, bypassing any error
+ * 				injection that could drop the completion.
+ * @rq: Request to be force completed
+ *
+ * Drivers should use blk_mq_complete_request() to complete requests in their
+ * normal IO path. For timeout error recovery, drivers may call this forced
+ * completion routine after they've reclaimed timed out requests to bypass
+ * potentially subsequent fake timeouts.
+ */
+void blk_mq_force_complete_rq(struct request *rq)
 {
 	struct blk_mq_ctx *ctx = rq->mq_ctx;
 	struct request_queue *q = rq->q;
@@ -602,6 +612,7 @@ static void __blk_mq_complete_request(struct request *rq)
 	}
 	put_cpu();
 }
+EXPORT_SYMBOL_GPL(blk_mq_force_complete_rq);
 
 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
 	__releases(hctx->srcu)
@@ -635,7 +646,7 @@ bool blk_mq_complete_request(struct request *rq)
 {
 	if (unlikely(blk_should_fake_timeout(rq->q)))
 		return false;
-	__blk_mq_complete_request(rq);
+	blk_mq_force_complete_rq(rq);
 	return true;
 }
 EXPORT_SYMBOL(blk_mq_complete_request);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index d7307795439a..856bb10993cf 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -494,6 +494,7 @@ void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
 void blk_mq_kick_requeue_list(struct request_queue *q);
 void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
 bool blk_mq_complete_request(struct request *rq);
+void blk_mq_force_complete_rq(struct request *rq);
 bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,
 			   struct bio *bio, unsigned int nr_segs);
 bool blk_mq_queue_stopped(struct request_queue *q);
-- 
2.24.1


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Re: [PATCHv3 1/2] blk-mq: export blk_mq_force_complete_rq

[Christoph Hellwig]

On Fri, May 29, 2020 at 07:37:43AM -0700, Keith Busch wrote:
> For when drivers have a need to bypass error injection.

The subject doesn't quite match the content, and the commit log in
general could be a little more verbose.  The changes itself look
fine to me.

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[PATCHv3 2/2] nvme: force complete cancelled requests

[Keith Busch]

Use blk_mq_foce_complete_rq() to bypass fake timeout error injection so
that request reclaim may proceed.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ba860efd250d..891e9461bfae 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -310,7 +310,7 @@ bool nvme_cancel_request(struct request *req, void *data, bool reserved)
 		return true;
 
 	nvme_req(req)->status = NVME_SC_HOST_ABORTED_CMD;
-	blk_mq_complete_request(req);
+	blk_mq_force_complete_rq(req);
 	return true;
 }
 EXPORT_SYMBOL_GPL(nvme_cancel_request);
-- 
2.24.1


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